With development of the Internet, users pay increasing attention to speed and results of website browsing. However, visit quality is seriously affected by the significantly-increased Internet user (netizen) numbers and the increased length of access path to a website. This is particularly the case when the access path to the website gets jammed by a suddenly-occurred large data volume. It is desirable to address such unsatisfied visit quality to access the Internet, especially in regions with increased number of non-local network users.
Content delivery network (CDN) adds a new layer of network structure to existing Internet architecture. CDN is able to deliver website content to a network “border” closest to a user. This is convenient for users to access the website content and to have an increased response speed for the users to access websites.
As shown in FIG. 1, when a user visits a website that participates CDN services, the best CDN node closest to the user can be identified by a domain name system (DNS) using re-directing technologies. Meanwhile, a request from the user is directed to this CDN node. When the user's request reaches the designated node, a CDN server (e.g., a high speed cache at the node) provides the user with the user requested content. The detailed procedure is as follows. A user input a domain name of a website to be visited in a browser for the browser to inquiry a local DNS to resolve the domain name. The local DNS sends the request to a main DNS of the website. The main DNS identifies the most appropriate CDN node based on a series of strategies and send the resolved result (i.e., an IP address) to the user. The user can then request content corresponding to the website from the designated CDN node.
For companies with large amount of users, user-visit-volume to an access layer is generally huge on an annual basis and sometimes can even reach a top level. Therefore, these companies, in addition to building their own CDN to accommodate users' visits to the access layer, may purchase services from external CDN service providers to share the volume burden. Due to security concerns, companies are intended to purchase services from different CDN service providers, instead of solely relying on a single CDN service provider. For example, if the overall business visit volume of a company is 1000 G, the company itself may handle 800 G out of the 1000 G, with 100 G out of this 1000 G handled by CDN service provider A and another 100 G out of this 1000 G handled by CDN service provider B. The core resource bandwidth of a CDN server is often provided by an infrastructure operator. Therefore, the capacity of the company to build the CDN on its own depends on negotiations with the infrastructure operator. Once own resources become shortage, the company has to be able to timely allocate a portion of network traffic to external CDN service providers. Therefore, there is a need for a real-time control for allocating CDN volume to the access layer.